Fiber reinforced concrete is superior to plain concrete in toughness, which is the energy absorption at fracture. This study is intended to use fibers extracted from bamboo for tensile reinforcement of concrete. Some experiments were carried out to explore the possibility of bamboo fiber reinforced concrete. As a result, the compressive strength of concrete with 1-2% bamboo fiber is little different from the case without reinforcement. On the other, the splitting tensile and the flexural strength significantly increased with an increased volume fraction of fibers. The strength of bamboo fiber reinforced concrete increased with increasing fiber content as a result of fiber bridging.

Recently, in the attention in response to global warming issues and sustainable society, the manufacturing using natural materials has become actively. Bamboo, low cost, fast growing, and broad distribution of growth, is expected to contribute significantly to earthquake-resistant construction and seismic retrofit technology for developing countries. This report has been prepared to assist the seismic retrofit of the masonry structures in the design and construction of bamboo reinforced concrete. A study of the feasibility of using bamboo and non-steel as the reinforcing material in concrete members was conducted in our laboratory. Six beam specimens were constructed and a total of 11 beam tests were performed to examine the flexural cracking and the shear cracking strength. Additionally, monotonic compression tests were carried out on 16 column specimens, which has 200mm in diameter and 500mm in height with confining steel bars or PP-band spirals, in order to study fracture behavior and mechanical property of bamboo confined concrete. (C) 2011 Published by Elsevier Ltd. Selection and peer-review under responsibility of ICM11

Authors have proposed High tension bolted friction slip damper with higher friction coefficients than conventional ones, so the dynamic loading tests have conducted by using the bolted friction slip connection specimens that sandwiched aluminum alloy sliding plates. In addition, for stabilization of frictional slipping behavior, specimens were also sandwiched by rubber washers. The purpose of this study is a proposal of new hybrid friction damper, which absorbs the vibration energy on both wind load and seismic load. In this paper, in order to describe the charcteristics of this damper, dainamic loading tests were conducted and an anlysis model of the damper was also proposed.

The earthquake-resistant steel bar named FLS is developed for the high performance of reinforced concrete members against the earthquake by Center for High-Tech Research Fukuyama University. The mechanical property of the steel is low yield strength and high ductility. The influence of the steel bar do to earthquake energy consumption in formation of the plastic hinge of RC members is considered. This paper describes the seismic performance of RC specimens with FLS and an application example in a seismic reinforcement.

筆者らは,地震エネルギーを効果的に吸収させる耐震性新鋼材を開発してきた。本論では,この耐震性新鋼材による棒鋼を平行主筋あるいはX形主筋として組み込んだ鉄筋コンクリートの曲げ部材の実験を行い,その耐震性能の検討を行った。その結果,耐震性新鋼材を主筋に用いると,普通鋼材を用いた場合に比して,変位振幅の増加にともなって等価粘性減衰定数が大きくなり,耐震性能の向上に寄与することを示した。

For developing high tension bolted frictional-slippage damper with much higher friction coefficients than conventional ones, the dynamic loading tests were conducted by using the bolted frictional-slippage connection specimens that sandwiched aluminum alloy sliding plates. In addition, for stabilization of frictional slipping behavior, specimens were also sandwiched by rubber washers. As the results, specimens using aluminum alloy sliding plates and rubber washer showed stable frictional slipping behavior. The results of these tests showed that slip coefficient of more than 0.60 for A1050P aluminum sliding plates and invariable slip coefficient of 0.36 for A2017P were confirmed respectively.

大地震に対する建築構造物の耐震性能向上を図る目的で,地震エネルギーが効果的に吸収,散逸される先端材料の高延性鋼材を組み込んだ新構造システムを考察して,構造物の被害を最小限に抑え,その機能性を確保する先端的な耐震設計法を開発する。本研究では,耐震性新鋼材を主筋として組み込んだRC曲げ部材の実験を行い,その耐震性能を評価するとともに,簡単な断面解析を行い,実験結果との比較・検討も行った。その結果,耐震性新鋼材を主筋に用いると,鉄筋コンクリート部材の曲げ塑性ヒンジにおいて,等価粘性減衰が大きく,耐力劣化がない紡錘型の履歴性状が示された。

主筋として使われている鋼材の力学的性能を規定する諸数値が,鉄筋コンクリート部材の塑性ヒンジの形成における地震エネルギー消費に対してどのような関わりを持つのか,さらに,適正に塑性変形を制御するためには,鋼材の諸数値としてどのような値を与えればよいのかを解析的に検討した。解析の結果より,降伏後の剛性が大きい鋼材を利用したほうが,小さな塑性変形で大きな地震エネルギー消費を期待できることが確認された。

コンクリートのような脆性材料の非線形な変形挙動をより柔軟に表現するために,様々な寸法,密度,方向を持った微視ひびわれの進展挙動を線形破壊力学の観点からモデル化し,連続体として扱えるコンクリート構成則を構築した.まず,微視クラヅクの非弾性挙動を陽な形で反映したコンクリートのモデル化を行い,構成則を導出する過程およびその考え方を示した.そして,この構成式を有限要素プログラムに組み込んだ数値解析手法を用いて,一軸荷重下にあるコンクリート部材の数値計算を行い,巨視応答における破壊過程の再現性を確認した.

コンクリートの非線形挙動はひび割れの発生・成長に特徴づけられているため,ひび割れの局所化現象などの力学挙動を正しく捉えるためには,これらひび割れの力学挙動に着目した構成則モデルの開発が必要である.本研究では,微視クラックの非弾性挙動を陽な形で反映したコンクリートのモデル化を行い,構成則を導出する過程およびその考え方を示した.そして,この構成式を有限要素プログラムに組み込んだ数値解析手法で,一軸圧縮荷重を受けるコンクリート部材の数値シミュレーションを行った.

RCラーメン架構iの最上階外柱梁接合部内に90。折り曲げ定着された梁上端筋を対象にして、水平投影定着長、余長部長、コンクリート強度、横補強筋比、梁筋径、梁筋強度、折曲げ半径が定着破壊性状に及ぼす影響を実験的に検討し、これらの影響要因に対する破壊形式を分類し、定着耐力に与える影響を明らかにした。

筆者らは、鉛直力と岡時に面外水平力を受ける計8体のRC造壁スラブ交差部の実験を行い、その破壌性状の把握と耐震性能の向上について検討してきた。本報はこのうち内部交差部3体の試験体を対象として、有限要素法を用いてその諸性状について検討した。PCaスラブかかりしろ部分のモデル化により、実験で得た荷重変形特性はおおむね再現できるようになり、壁の軸応力度の増大に伴うせん断耐力の増加や、スラブ成中央近くに配筋されたスラブ主筋の性状が解析結果でも示された.

Recently, in the attention in response to global warming issues and sustainable society, the manufacturing using natural materials has become actively. Bamboo, low cost, fast growing, and broad distribution of growth, is expected to contribute significantly to earthquake-resistant construction and seismic retrofit technology for developing countries. This report has been prepared to assist the seismic retrofit of the masonry structures in the design and construction of bamboo reinforced concrete. A study of the feasibility of using bamboo and non-steel as the reinforcing material in concrete members was conducted in our laboratory. Six beam specimens were constructed and a total of 11 beam tests were performed to examine the flexural cracking and the shear cracking strength. Additionally, monotonic compression tests were carried out on 16 column specimens, which has 200mm in diameter and 500mm in height with confining steel bars or PP-band spirals, in order to study fracture behavior and mechanical property of bamboo confined concrete. (C) 2011 Published by Elsevier Ltd. Selection and peer-review under responsibility of ICM11

When conducting seismic evaluation of existing buildings it is necessary to clarify the differences in the properties of reinforced concrete members and material obtained from existing buildings and concrete manufactured in the laboratory. In this study, the seismic tests were performed using the actual material and RC members. The following conclusions can be made. (1) The current equations to determine the failure mode of RC members shown in the standard are almost appropriate. (3)In the flexural members, the bond slipping failure can occur after the yielding of the main bars.(2) Properties of concrete of the old building were distributed in a very wide range and their coefficient of variation were significantly large. (5) Epoxy resin injection improved the shear performance of the RC members regardless of the failure mode.

When conducting seismic evaluation of existing buildings it is necessary to clarify the differences in the properties of material and reinforced concrete members obtained from existing buildings and concrete manufactured in the laboratory. In this study, the seismic tests were performed using the actual material and members. The following conclusions can be made. (1) Observed modulus of elasticity of concrete was lower than the estimated values calculated from the present equation. (2) Tensile strength could be predicted by the present equation. (3) The present equation for the strength of shear crack recommended in the standard tends for RC members to significantly underestimate the observed value of the original members.(4) The present equation for shear capacity could predict the observed value considering the reduction factors for the lightweight and low strength concrete. (5) Epoxy resin injection significantly improved the seismic performance of the RC members.

This study presents the seismic performance of existing buildings with low strength concrete less than 13. 5N/ mm^2. The experimental works using those members were performed. The effects of retrofitting were also investigated through the loading tests. The present equations could predict the maximum strength of those members and the jacketing method is effective to increase the seismic performance. It is found that epoxy resin injection was significantly effective to improve the bond characteristics of the plain round bars

A group of faculty member of the department of Civil Engineering, Architecture and Mechanical Engineering is now studying on a common theme “Research Project on Improvements in Seismic Performance of Structures" from various aspect of research. In this project, the influence which a few coefficients determine a mechanical performance of main bars do to earthquake energy consumption in formation of the plastic hinge of RC members was considered. Then Earthquake-Resistant Steel have been developed in this group. (1) The development of more ductile materials for the seismic performance involves next steps : Set 0.2% proof stress to about 100-150MPa, tensile stress to 400MPa, and elongation to 30% or greater as target values for the material. Tensile tests were carried out on several tens of several alloys produced for this investigation. Fe-4Ni-14Cr-24Mn alloy was selected as a suitable candidate. A semi-production heat of this steel was made. Hot-rolled and annealed steel plate exhibited 0.2% proof stress of 118MPa, tensile strength of 448MPa and elongation of 28%. (2)Experimental results of steel columns fabricated using Earthquake-resistant steel plates are presented. The experiments have been conducted to investigate the effects of mold line of taper plates, tapering ratio, stiffeners rigidity, and tapered stiffeners. Further studies are needed for improved strength and ductility of shear-type seismic devices. (3) It is confirmed that the energy dissipation of RC members with Earthquake-resistant steel bars increased greatly as seismic devices. The seismic performance on a existing building, adopted the seismic retrofit using the present RC member, are preformed to show the applicability of it's reinforcement.